EP2756187A2 - Fluid turbine lightning protection system - Google Patents

Fluid turbine lightning protection system

Info

Publication number
EP2756187A2
EP2756187A2 EP12806193.4A EP12806193A EP2756187A2 EP 2756187 A2 EP2756187 A2 EP 2756187A2 EP 12806193 A EP12806193 A EP 12806193A EP 2756187 A2 EP2756187 A2 EP 2756187A2
Authority
EP
European Patent Office
Prior art keywords
fluid turbine
shroud
electrically conductive
conductive material
lightning
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP12806193.4A
Other languages
German (de)
French (fr)
Other versions
EP2756187B1 (en
Inventor
Rasmus Peter JENSEN
Soren Hjort
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ogin Inc
Original Assignee
Ogin Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ogin Inc filed Critical Ogin Inc
Publication of EP2756187A2 publication Critical patent/EP2756187A2/en
Application granted granted Critical
Publication of EP2756187B1 publication Critical patent/EP2756187B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/04—Wind motors with rotation axis substantially parallel to the air flow entering the rotor  having stationary wind-guiding means, e.g. with shrouds or channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • F03D80/30—Lightning protection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • the present disclosure relates to the field of wind turbines and more particularly to the protection of shrouded turbines from lightning strikes.
  • Utility scale wind turbines used for power generation may have one to five open blades comprising a rotor.
  • the rotor transforms wind energy into a rotational torque that drives at least one generator rotationally coupled to the rotor, either directly or through a transmission assembly, to convert mechanical energy to electrical energy.
  • Such turbines typically have long blades that are the most susceptible component of the wind turbine to lightning strikes.
  • Wind turbines are required to be equipped with lightning protection systems in order to conduct large currents from lightning strikes to the ground without damaging the components of the turbine. Lightning strikes pose a threat to the blades, metallic rotational equipment, and electronic components. Increased density in wind farms poses additional threats from lightning strikes.
  • Blades comprised of weakly conductive material such as carbon fiber or other fiber reinforced polymers, experience high currents and therefore excessive heat when struck by lightning.
  • External protective conductors such as lightning rods, are impractical on a fast moving aerodynamic structure such as a blade.
  • a protective mesh allows for a conductive layer without external conductors, however, the point of contact of a lightning strike will often damage the composite surface and provide a stress point where a crack can form.
  • Conventional wind turbine blades are typically engaged with bearing systems between the blades and a hub, a shaft and a nacelle, and between the nacelle and a tower.
  • the blades are typically engaged with a bearing system at the root, and rotate about their long axis to alter the chord angle with respect to the wind direction for control of the rotor rotational speed with respect to the wind speed.
  • the set of blades are further engaged with a hub that is connected to a shaft engaged with a bearing system within the generator.
  • the shaft is rotationally engaged with the bearing system within the generator and drives the generator.
  • the nacelle rotates about the support structure to yaw the turbine with respect to the wind direction and, for this reason, is engaged with a yaw bearing system between the nacelle and the tower.
  • the bearing systems of the wind turbine as described above may provide a spark gap and can be damaged by high current passage.
  • lightning striking the tip of a blade needs to be conducted through three bearing systems before reaching a direct connection to the ground.
  • wind turbines may be equipped with meteorological equipment and sensitive electronic equipment that can be damaged by minor lightning strikes.
  • the present disclosure relates to a shrouded fluid turbine lightning protection system, a shrouded fluid turbine system comprising a lightning protection system, and a method of protecting a shrouded fluid turbine from a lightning strike.
  • An example embodiment of a shrouded fluid turbine lightning protection system includes at least one air termination device that can be positioned on a shroud of a fluid turbine.
  • the at least one air termination device is formed at least in part of an electrically conductive material and in electrical communication with a down conduction system.
  • the down conduction system is in electrical communication with an earth- termination system that is configured to dissipate electricity transferred thereto to the ground.
  • the at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground.
  • the shrouded fluid turbine may include a turbine shroud, and the at least one air termination device may also be positionable on the turbine shroud.
  • the shrouded fluid turbine may include an ejector shroud, and the at least one air termination device may also be positionable on the ejector shroud.
  • An electrically conductive material may be integrated with the turbine shroud and/or the ejector shroud and electrically engaged with the down conductive system.
  • the electrically conductive material may be positioned on a leading or trailing edge of the turbine shroud, a leading or trailing edge of the ejector shroud, or integrated with the surface of either the turbine shroud or the ejector shroud.
  • An example embodiment relates in general, to a shrouded fluid turbine comprising a ringed turbine shroud that surrounds a rotor, and at least one air termination device positioned on the shroud of the fluid turbine.
  • the at least one air termination device is formed at least in part of an electrically conductive material and in electrical communication with a down conduction system.
  • the down conduction system is in electrical communication with an earth-termination system that is configured to dissipate electricity transferred thereto to the ground.
  • the at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground.
  • This embodiment may further comprise an ejector shroud that surrounds the exit of the turbine shroud.
  • the turbine shroud may comprise a set of mixing lobes along the trailing edge.
  • the set of mixing lobes along the trailing edge are in fluid communication with the inlet of the ejector shroud.
  • the mixer lobes and the ejector shroud form a mixer-ejector pump that provides increased fluid velocity near the inlet of the turbine shroud, at the cross sectional area of the rotor plane.
  • the mixer- ejector pump further provides a means of energizing the wake behind the rotor plane.
  • the combination of the effects of the mixing lobes and the energized wake provide a rapidly-mixed, short wake when compared to non-shrouded horizontal axis wind turbines.
  • the at least one air termination device may also be positionable on the ejector shroud.
  • An electrically conductive material may be integrated with the turbine shroud and/or the ejector shroud and electrically engaged with the down conductive system.
  • the electrically conductive material may be positioned on a leading or trailing edge of the turbine shroud, a leading or trailing edge of the ejector shroud, or integrated with the surface of either the turbine shroud or the ejector shroud.
  • An example embodiment relates to a method of protecting a shrouded fluid turbine from a lightning strike.
  • a shrouded fluid turbine is provided and a peak lightning strike current is determined for the shrouded fluid turbine.
  • One or more air termination devices are positioned on the shroud such that the calculated "Rolling Sphere" will contact the one or more air termination devices before contacting the shroud when the "Rolling Sphere" is rolled along an exterior of the shroud.
  • the present embodiment discloses a Primary Lightning Protection system (LPS) and a Secondary Lightning Protection System (LPS2).
  • LPS is intended to intercept and conduct lightning strikes of a range from approximately >25kA to ⁇ 200 kA, safely from the air-termination system through the down conduction system to the earth-termination system.
  • the corresponding rolling sphere system includes a range of radii from >81m to ⁇ 313m.
  • a secondary lightning protection system (LPS2) is comprised of materials integral to the shroud surfaces in combination with a down conduction system to the earth-termination system.
  • the LPS2 is intended to intercept and conduct lightning strikes of a range from approximately >3kA to ⁇ 10 kA usually in the form of static electricity. These charges correspond to a rolling sphere radius of 20m.
  • the turbine shroud and/or the ejector shroud provide a platform for an integrated lightning protection system resulting in a system with reduced complexity when compared to the lightning protection systems of horizontal axis wind turbines.
  • the turbine shroud and/or the ejector shroud include few to no electrical components or mechanical moving parts, thus further reducing the risk of critical damage to the shrouded turbine.
  • Figure 1 is a front, right, perspective view of an example embodiment of the present disclosure
  • Figure 2 is a front, orthographic view of the example embodiment of Figure l;
  • Figure 3 is a side, orthographic view of the example embodiment of Figure l;
  • Figure 4 is a front, orthographic view of an example embodiment of the present disclosure.
  • Figure 5 is a side, orthographic view of the example embodiment of Figure 4.
  • Figure 6 is a front, orthographic view of an example embodiment of the present disclosure.
  • Figure 7 is a side, orthographic view of the example embodiment of Figure 6;
  • Figure 8 is a front, right, perspective, detail view of an example embodiment of the present disclosure.
  • Figure 9 is a right, perspective, detail view of the example embodiment of Figure 8.
  • Figure 10 is a front, right, perspective view of an example embodiment of the present disclosure.
  • Figure 11 is a front, orthographic view of the example embodiment of Figure 10.
  • Figure 12 is a side, orthographic view of the example embodiment of Figure 10.
  • a Mixer-Ejector Turbine provides an improved means of generating power from fluid currents.
  • the Mixer- Ejector Turbine includes tandem cambered shrouds and a mixer/ejector pump.
  • the primary shroud contains a rotor, which extracts power from a primary fluid stream.
  • the tandem cambered shrouds and ejector bring more flow through the rotor allowing more energy extraction due to higher flow rates.
  • the mixer/ejector pump transfers energy from the bypass flow to the rotor wake flow allowing higher energy per unit mass flow rate through the rotor.
  • a shrouded turbine provides an improved means of generating power from fluid currents.
  • the shrouded turbine includes only a single shroud and does not include a mixer/ejector pump.
  • the sole shroud contains a rotor, which extracts power from a primary fluid stream.
  • rotor is used herein to refer to any assembly in which one or more blades are attached to a shaft and able to rotate, allowing for the extraction of power or energy from fluid (wind or water) rotating the blades.
  • exemplary rotors include a propeller-like rotor or a rotor/stator assembly. Any type of rotor may be enclosed within the turbine shroud in the shrouded turbine of the present disclosure.
  • the leading edge of a turbine shroud may be considered the front of the fluid turbine, and the trailing edge the turbine shroud may be considered the rear of the fluid turbine. In embodiments with an ejector shroud, the trailing edge of the ejector shroud may be considered the rear of the fluid turbine.
  • a first component of the fluid turbine located closer to the front of the turbine may be considered “upstream” of a second component located closer to the rear of the turbine. Put another way, the second component is "downstream" of the first component.
  • the present disclosure relates to a shrouded fluid turbine that includes a turbine shroud that surrounds a rotor and an integrated lightning protection system that employs the structure and surfaces of the shroud.
  • the present disclosure relates to a shrouded fluid turbine that includes a turbine shroud that surrounds a rotor, an ejector shroud that surrounds the exit of the turbine shroud and an integrated lightning protection system that employs the structure and surfaces of the shrouds.
  • An example external lightning protection system may consist of an air-termination system, a down conduction system, and an earth termination system.
  • An air-termination system also known as a lightning rod, is a component of an external lightning protection system intended to intercept lightning flashes.
  • a down conduction system is a conductor that is intended to conduct the lightning current from the air- termination system to the earth-termination system.
  • An earth-termination system is a network of electrically interconnected rods, plates, mats, piping, grids, or other conductive components, installed below grade to establish a low resistance contact with the earth.
  • Rolling Sphere One method of determining the risk of direct lightning attachment is known as the "Rolling Sphere” method, in which an imaginary sphere is rolled about the surfaces of a 3D digital model of the wind turbine.
  • the radius of the sphere is defined as:
  • r is the rolling sphere radius in meters [m] and I is the Peak Current in kiloamperes [kA].
  • I is the Peak Current in kiloamperes [kA].
  • Figures 1 through 9 depict example embodiments of a shrouded fluid turbine having two shrouds.
  • Figure 1 is a perspective view of an exemplary embodiment of a shrouded fluid turbine of the present disclosure.
  • Figure 2 is a front view of the fluid turbine of Figure 1.
  • Figure 3 is a side view of the fluid turbine of Figure 1.
  • the shrouded fluid turbine 100 comprises a turbine shroud 110, an ejector shroud 120, a rotor 140, and a nacelle body 150.
  • the turbine shroud 110 includes a front end 112, also known as an inlet end or a leading edge, and a rear end or trailing edge 116, also known as an exhaust end.
  • the trailing edge 116 includes high energy lobes 117 and low energy lobes 115.
  • the depiction of the recited high energy lobes 117 and low energy lobes 115 is solely for illustrative purposes.
  • the ejector shroud 120 includes a front end 122, also known as an inlet end or leading edge, and a rear end or trailing edge 124, also known as an exhaust end.
  • Support members 106 connect the turbine shroud 110 to the ejector shroud 120.
  • the rotor 140 surrounds the nacelle body 150 and comprises a central hub 141 at the proximal end of the rotor blades.
  • the central hub 141 is rotationally engaged with the nacelle body 150.
  • the rotor 140, turbine shroud 110, and ejector shroud 120 are coaxial with each other, i.e., they share a common central axis 105.
  • At least one air termination device 161 between 1/80 to 1/20 the diameter of the ejector in length, is engaged with the turbine shroud 110. Additionally, at least one air termination device 164 between lm and 2m in length is also engaged with the ejector shroud 120.
  • FIG. 1 A Primary Lightning Protection system (LPS) is illustrated in Figures 1 through Figure 5.
  • Figure 4 is a front view of an example embodiment
  • Figure 5 is a side view of the example embodiment of Figure 4.
  • Figure 2 and Figure 3 depict a rolling sphere radius in relation to the outer surface of the fluid turbine 100.
  • the rolling sphere circumference is illustrated by arc 170 and the radius is illustrated by arrow 172.
  • the rolling sphere arcs 170 have an approximate diameter of 313 meters, which corresponds to a lightning current of up to 200 kA. It can be seen in Figures 2 and 3 that the arcs 170 do not come in contact with the body of the turbine shroud 110 or the ejector shroud 120 before coming in contact with at least one of the air termination devices 161/164.
  • the arcs 170 do not come in contact with the rotor 140, the hub 141, or the nacelle 150 before coming in contact with at least one of the air termination devices 161/164.
  • the air termination devices 161/164 are in electrical communication with a down conduction system 176 by way of electrically coupled first and second conductors 174/175.
  • the down conduction system 176 transfers electricity to an earth- termination system 178 for dispersion of the electricity.
  • Figure 4 and Figure 5 depict a rolling sphere radius of approximately 80 meters, which corresponds to a lightning current in the range of approximately >25kA to ⁇ 50 kA.
  • the rolling sphere circumference is depicted by arcs 270 and the radius is depicted by arrow 272. It can be seen in Figure 4 and Figure 5 that the rolling sphere has minimal contact with the turbine shroud 210 and the ejector shroud 220. Simultaneous contact of the rolling sphere with either of the turbine shroud 210 or the ejector shroud 220 and at least one of the air termination devices 261/264 is possible.
  • a secondary lightning protection system (LPS2) is illustrated in Figure 6 and Figure 7.
  • the LPS2 comprises electrically conductive materials integrated with the surfaces of a turbine shroud 310 and an ejector shroud 320.
  • the electrically conductive materials are connected with a down conduction system 376 by way of electrically coupled first and second conductors 374/375, the down conduction system 376 is connected to an earth-termination system 378.
  • Figure 6 and Figure 7 depict a rolling sphere radius of approximately 20 meters, which corresponds to a lightning current in the range of approximately >3kA to ⁇ 10 kA.
  • the rolling sphere circumference is depicted by arcs 370 and the radius is depicted by arrow 372.
  • the LPS2 is intended to intercept and conduct lightning strikes of a range from approximately >3kA to ⁇ 10 kA usually in the form of static electricity.
  • various metal fasteners (not shown) on the surface of the turbine shroud 310 and the ejector shroud 320 provide a sufficient means of dissipating a static charge prior to contact with the rotor 340, the hub 341, or the nacelle 350.
  • shroud surfaces with embedded or integrated materials provide additional lightning protection to rotating and electrical generation components.
  • FIG. 8 and Figure 9 illustrate an air-termination system integrated into the shroud surfaces.
  • a mixer ejector turbine 400 comprises a turbine shroud 410 surrounding a rotor 440, engaged with a hub 441 that is further engaged with a nacelle 450.
  • An ejector shroud 420 has an inner diameter greater that the outer diameter of the trailing edge of the turbine shroud 410 and the injector shroud 420 and the turbine shroud 410 are concentric to one another.
  • the ejector shroud 420 surrounds the trailing edge of the turbine shroud 410.
  • the ejector shroud 420 is located downstream from the trailing edge of the turbine shroud 410.
  • a first electrically conductive material 470 is comprised of metalized polymers, fiber reinforced composites with electrically conductive fibers woven into the reinforcement, or composites with metallic characteristics such as those provided by nanoparticles made from graphite.
  • the first electrically conductive material 470 is engaged with the leading edge of the turbine shroud 410 and further conductively engaged with an internal structure 472 of the turbine shroud 410 that is both electrically conductive and insulated.
  • the internal structure 472 is further conductively engaged, through an electrical wiper system, as described below, with a down-conductive system 476 that is conductively engaged with an earth-termination system 478.
  • a second electrically conductive material 475 is engaged with the trailing edge of the ejector shroud 420 and is further conductively engaged with an internal structure 474 of the ejector shroud 420 that is further conductively engaged with the down-conductive system 476 that is conductively engaged with the earth-termination system 478.
  • Electrical wiper systems also known as slip rings, are commonly used to transfer electricity between stationary and rotating components and include conductive arms engaged with rotating disks.
  • the conductive arms are often formed of metal such as brass or copper with a combination carbon and metallic substance at the distal ends. The distal ends engage with the rotating disks and provide rotational electrical connectivity.
  • a mixer ejector turbine 500 comprises a turbine shroud 510 that surrounds a rotor 540, engaged with a hub 541 that is further engaged with a nacelle 550.
  • An ejector shroud 520 has an inner diameter greater than the outer diameter of the trailing edge of the turbine shroud 510, and the ejector shroud 520 and the turbine shroud 510 are concentric with one another.
  • the ejector shroud 520 surrounds the trailing edge of the turbine shroud 510.
  • the ejector shroud 520 is located downstream from the trailing edge of the turbine shroud 510.
  • a first electrically conductive material 580 is integrated into the surface of the turbine shroud 510 and further conductively engaged with an internal structure 572 of the turbine shroud that is conductively engaged 510 that is electrically conductive and insulated.
  • the internal structure 527 is further conductively engaged with a down- conductive system 576 that is conductively engaged to an earth-termination system 578.
  • a second electrically conductive material 586 is integrated into the surface of the ejector shroud 520 and is further conductively engaged with an internal structure 574 of the ejector shroud 520 that is electrically conductive and insulated.
  • the internal structure 574 is further conductively engaged with the down-conductive system 576 that is conductively engaged to the earth-termination system 578.
  • Figures 10 through 12 depict example embodiments of a single shroud fluid turbine.
  • Figure 10 is a perspective view of an exemplary embodiment of a single shroud fluid turbine of the present disclosure.
  • Figure 11 is a front view of the single shroud fluid turbine of Figure 10.
  • Figure 12 is a side view of the single shroud fluid turbine of Figure 10.
  • the single shrouded fluid turbine 600 comprises a turbine shroud 610, a rotor 640, and a nacelle body 650.
  • the turbine shroud 610 includes a front end 612, also known as an inlet end or a leading edge, and a rear end or trailing edge 616, also known as an exhaust end.
  • the trailing edge 616 includes high energy lobes 617 and low energy lobes 615.
  • the rotor 640 surrounds the nacelle body 650 and includes a central hub 641 at the proximal end of the rotor blades.
  • the central hub 641 is rotationally engaged with the nacelle body 650.
  • the rotor 640 and turbine shroud 610 are coaxial with each other, i.e., they share a common central axis 605.
  • At least one air termination device 661 between 1/80 to 1/20 the diameter of the turbine shroud 610 in length, is engaged with the leading edge 612 of the turbine shroud 610.
  • at least one air termination device 664 between lm and 2m in length is also engaged with the trailing edge 616 of the turbine shroud 610.
  • FIG. 10 A Primary Lightning Protection system (LPS) is illustrated in Figures 10 through Figure 12.
  • Figure 11 is a front view of an example embodiment
  • Figure 12 is a side view of the example embodiment of Figure 11.
  • Figure 11 and Figure 12 depict a rolling sphere radius in relation to the outer surface of the fluid turbine 600.
  • the rolling sphere circumference is illustrated by arc 670 and the radius is illustrated by arrow 672.
  • the rolling sphere arcs 670 have an approximate diameter of 313 meters, which corresponds to a lightning current of up to 200 kA. It can be seen in Figures 11 and 12 that the arcs 670 do not come in contact with the body of the turbine shroud 610 before coming in contact with at least one of the air termination devices 661/664.
  • the arcs 670 do not come in contact with the rotor 640, the hub 641, or the nacelle 650 before coming in contact with at least one of the air termination devices 661/664.
  • the air termination devices 661/664 are in electrical communication with a down conduction system 676 by way of an electrically coupled conductor 675.
  • the down conduction system 676 transfers electricity to an earth-termination system 678 for dispersion of the electricity.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Wind Motors (AREA)
  • Elimination Of Static Electricity (AREA)

Abstract

A fluid turbine lightning protection system includes at least one air termination device, formed at least in part of an electrically conductive material, that can be positioned on a shroud of a fluid turbine and placed in electrical communication with a down conduction system. The down conduction system is in electrical communication with an earth-termination system configured to dissipate electricity transferred thereto to the ground. The at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground. The at least one air termination device may be positioned on a turbine shroud based on a "Rolling Sphere" derivation wherein the "Rolling Sphere" derivation is derived from the equation r = 10 · I0.65, where I is the peak current in kiloamperes and r is the rolling sphere radius in meters.

Description

FLUID TURBINE LIGHTNING PROTECTION SYSTEM
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional patent application no. 61/534,467 filed on September 14, 2011, the contents of which is hereby incorporated by reference in their entirety.
BACKGROUND
[0002] The present disclosure relates to the field of wind turbines and more particularly to the protection of shrouded turbines from lightning strikes. Utility scale wind turbines used for power generation may have one to five open blades comprising a rotor. The rotor transforms wind energy into a rotational torque that drives at least one generator rotationally coupled to the rotor, either directly or through a transmission assembly, to convert mechanical energy to electrical energy. Such turbines typically have long blades that are the most susceptible component of the wind turbine to lightning strikes. Wind turbines are required to be equipped with lightning protection systems in order to conduct large currents from lightning strikes to the ground without damaging the components of the turbine. Lightning strikes pose a threat to the blades, metallic rotational equipment, and electronic components. Increased density in wind farms poses additional threats from lightning strikes.
[0003] Blades comprised of weakly conductive material such as carbon fiber or other fiber reinforced polymers, experience high currents and therefore excessive heat when struck by lightning. External protective conductors, such as lightning rods, are impractical on a fast moving aerodynamic structure such as a blade. Alternatively, a protective mesh allows for a conductive layer without external conductors, however, the point of contact of a lightning strike will often damage the composite surface and provide a stress point where a crack can form.
[0004] Conventional wind turbine blades are typically engaged with bearing systems between the blades and a hub, a shaft and a nacelle, and between the nacelle and a tower. The blades are typically engaged with a bearing system at the root, and rotate about their long axis to alter the chord angle with respect to the wind direction for control of the rotor rotational speed with respect to the wind speed. In addition to this bearing system, the set of blades are further engaged with a hub that is connected to a shaft engaged with a bearing system within the generator. The shaft is rotationally engaged with the bearing system within the generator and drives the generator. The nacelle rotates about the support structure to yaw the turbine with respect to the wind direction and, for this reason, is engaged with a yaw bearing system between the nacelle and the tower. The bearing systems of the wind turbine as described above may provide a spark gap and can be damaged by high current passage. In this described example wind turbine, lightning striking the tip of a blade needs to be conducted through three bearing systems before reaching a direct connection to the ground.
[0005] Additionally, wind turbines may be equipped with meteorological equipment and sensitive electronic equipment that can be damaged by minor lightning strikes.
[0006] As the density of turbines in a wind farm increases, the potential for a single lightning strike to damage more than one turbine increases. Electrical installations, such as overhead lines, may provide protective conductors arranged around or above the installation. However, horizontal axis wind turbines having open blades present an obstacle to such protective conductors.
SUMMARY
[0007] The present disclosure relates to a shrouded fluid turbine lightning protection system, a shrouded fluid turbine system comprising a lightning protection system, and a method of protecting a shrouded fluid turbine from a lightning strike.
[0008] An example embodiment of a shrouded fluid turbine lightning protection system includes at least one air termination device that can be positioned on a shroud of a fluid turbine. The at least one air termination device is formed at least in part of an electrically conductive material and in electrical communication with a down conduction system. The down conduction system is in electrical communication with an earth- termination system that is configured to dissipate electricity transferred thereto to the ground. The at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground. The at least one air termination device may be positioned on a turbine shroud based on a "Rolling Sphere" method wherein the "Rolling Sphere" method is derived from the equation r = 10 · I0'65, where I is the peak current in kiloamperes and r is the rolling sphere radius in meters. The shrouded fluid turbine may include a turbine shroud, and the at least one air termination device may also be positionable on the turbine shroud. The shrouded fluid turbine may include an ejector shroud, and the at least one air termination device may also be positionable on the ejector shroud. An electrically conductive material may be integrated with the turbine shroud and/or the ejector shroud and electrically engaged with the down conductive system. The electrically conductive material may be positioned on a leading or trailing edge of the turbine shroud, a leading or trailing edge of the ejector shroud, or integrated with the surface of either the turbine shroud or the ejector shroud.
[0009] An example embodiment relates in general, to a shrouded fluid turbine comprising a ringed turbine shroud that surrounds a rotor, and at least one air termination device positioned on the shroud of the fluid turbine. The at least one air termination device is formed at least in part of an electrically conductive material and in electrical communication with a down conduction system. The down conduction system is in electrical communication with an earth-termination system that is configured to dissipate electricity transferred thereto to the ground. The at least one air termination device is configured to intercept a lightning strike and direct it through the down conduction system, the earth-termination system, and into the ground. The at least one air termination device may be positioned on a turbine shroud based on a "Rolling Sphere" method wherein the "Rolling Sphere" method is derived from the equation r = 10 · I0'65, where I is the peak current in kiloamperes and r is the rolling sphere radius in meters. This embodiment may further comprise an ejector shroud that surrounds the exit of the turbine shroud.
[0010] In one embodiment, the turbine shroud may comprise a set of mixing lobes along the trailing edge.
[0011] In one embodiment, the set of mixing lobes along the trailing edge are in fluid communication with the inlet of the ejector shroud. Together, the mixer lobes and the ejector shroud form a mixer-ejector pump that provides increased fluid velocity near the inlet of the turbine shroud, at the cross sectional area of the rotor plane. The mixer- ejector pump further provides a means of energizing the wake behind the rotor plane. The combination of the effects of the mixing lobes and the energized wake provide a rapidly-mixed, short wake when compared to non-shrouded horizontal axis wind turbines. The at least one air termination device may also be positionable on the ejector shroud. An electrically conductive material may be integrated with the turbine shroud and/or the ejector shroud and electrically engaged with the down conductive system. [0012] The electrically conductive material may be positioned on a leading or trailing edge of the turbine shroud, a leading or trailing edge of the ejector shroud, or integrated with the surface of either the turbine shroud or the ejector shroud.
[0013] An example embodiment relates to a method of protecting a shrouded fluid turbine from a lightning strike. In the example method, a shrouded fluid turbine is provided and a peak lightning strike current is determined for the shrouded fluid turbine. A "Rolling Sphere" circumference is calculated based on the equation r = 10 · I0'65, where I is the peak current in kiloamperes and r is the rolling sphere radius in meters. One or more air termination devices are positioned on the shroud such that the calculated "Rolling Sphere" will contact the one or more air termination devices before contacting the shroud when the "Rolling Sphere" is rolled along an exterior of the shroud.
[0014] The present embodiment discloses a Primary Lightning Protection system (LPS) and a Secondary Lightning Protection System (LPS2). The LPS is intended to intercept and conduct lightning strikes of a range from approximately >25kA to <200 kA, safely from the air-termination system through the down conduction system to the earth-termination system. The corresponding rolling sphere system includes a range of radii from >81m to <313m. A secondary lightning protection system (LPS2) is comprised of materials integral to the shroud surfaces in combination with a down conduction system to the earth-termination system. The LPS2 is intended to intercept and conduct lightning strikes of a range from approximately >3kA to <10 kA usually in the form of static electricity. These charges correspond to a rolling sphere radius of 20m.
[0015] The turbine shroud and/or the ejector shroud provide a platform for an integrated lightning protection system resulting in a system with reduced complexity when compared to the lightning protection systems of horizontal axis wind turbines. The turbine shroud and/or the ejector shroud include few to no electrical components or mechanical moving parts, thus further reducing the risk of critical damage to the shrouded turbine. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The following is a brief description of the drawings, which are presented for the purposes of illustrating the disclosure set forth herein and not for the purposes of limiting the same.
[0017] Figure 1 is a front, right, perspective view of an example embodiment of the present disclosure;
[0018] Figure 2 is a front, orthographic view of the example embodiment of Figure l;
[0019] Figure 3 is a side, orthographic view of the example embodiment of Figure l;
[0020] Figure 4 is a front, orthographic view of an example embodiment of the present disclosure;
[0021] Figure 5 is a side, orthographic view of the example embodiment of Figure 4;
[0022] Figure 6 is a front, orthographic view of an example embodiment of the present disclosure;
[0023] Figure 7 is a side, orthographic view of the example embodiment of Figure 6;
[0024] Figure 8 is a front, right, perspective, detail view of an example embodiment of the present disclosure;
[0025] Figure 9 is a right, perspective, detail view of the example embodiment of Figure 8;
[0026] Figure 10 is a front, right, perspective view of an example embodiment of the present disclosure;
[0027] Figure 11 is a front, orthographic view of the example embodiment of Figure 10; and
[0028] Figure 12 is a side, orthographic view of the example embodiment of Figure 10.
DETAILED DESCRIPTION
[0029] A more complete understanding of the components, processes, and apparatuses disclosed herein can be obtained by reference to the accompanying figures. These figures are intended to demonstrate the present disclosure and are not intended to show relative sizes and dimensions or to limit the scope of the exemplary embodiments.
[0030] Although specific terms are used in the following description, these terms are intended to refer only to particular structures in the drawings and are not intended to limit the scope of the present disclosure. It is to be understood that like numeric designations refer to components of like function.
[0031] The term "about" when used with a quantity includes the stated value and also has the meaning dictated by the context. For example, it includes at least the degree of error associated with the measurement of the particular quantity. When used in the context of a range, the term "about" should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the range "from about 2 to about 4" also discloses the range "from 2 to 4."
[0032] A Mixer-Ejector Turbine (MET) provides an improved means of generating power from fluid currents. The Mixer- Ejector Turbine includes tandem cambered shrouds and a mixer/ejector pump. The primary shroud contains a rotor, which extracts power from a primary fluid stream. The tandem cambered shrouds and ejector bring more flow through the rotor allowing more energy extraction due to higher flow rates. The mixer/ejector pump transfers energy from the bypass flow to the rotor wake flow allowing higher energy per unit mass flow rate through the rotor. These two effects enhance the overall power production of the turbine system.
[0033] A shrouded turbine provides an improved means of generating power from fluid currents. The shrouded turbine includes only a single shroud and does not include a mixer/ejector pump. The sole shroud contains a rotor, which extracts power from a primary fluid stream.
[0034] The term "rotor" is used herein to refer to any assembly in which one or more blades are attached to a shaft and able to rotate, allowing for the extraction of power or energy from fluid (wind or water) rotating the blades. Exemplary rotors include a propeller-like rotor or a rotor/stator assembly. Any type of rotor may be enclosed within the turbine shroud in the shrouded turbine of the present disclosure.
[0035] The leading edge of a turbine shroud may be considered the front of the fluid turbine, and the trailing edge the turbine shroud may be considered the rear of the fluid turbine. In embodiments with an ejector shroud, the trailing edge of the ejector shroud may be considered the rear of the fluid turbine. A first component of the fluid turbine located closer to the front of the turbine may be considered "upstream" of a second component located closer to the rear of the turbine. Put another way, the second component is "downstream" of the first component.
[0036] In one embodiment, the present disclosure relates to a shrouded fluid turbine that includes a turbine shroud that surrounds a rotor and an integrated lightning protection system that employs the structure and surfaces of the shroud. In some embodiments, the present disclosure relates to a shrouded fluid turbine that includes a turbine shroud that surrounds a rotor, an ejector shroud that surrounds the exit of the turbine shroud and an integrated lightning protection system that employs the structure and surfaces of the shrouds.
[0037] Various standards for lightning protection of wind turbines exist, and, as such, lightning protection systems typically employ a multi-faceted approach to the reduction of risk. An example external lightning protection system may consist of an air-termination system, a down conduction system, and an earth termination system. An air-termination system also known as a lightning rod, is a component of an external lightning protection system intended to intercept lightning flashes. A down conduction system is a conductor that is intended to conduct the lightning current from the air- termination system to the earth-termination system. An earth-termination system is a network of electrically interconnected rods, plates, mats, piping, grids, or other conductive components, installed below grade to establish a low resistance contact with the earth.
[0038] One method of determining the risk of direct lightning attachment is known as the "Rolling Sphere" method, in which an imaginary sphere is rolled about the surfaces of a 3D digital model of the wind turbine. The radius of the sphere is defined as:
r = 10 · I0,65
[0039] where r is the rolling sphere radius in meters [m] and I is the Peak Current in kiloamperes [kA]. For given rolling sphere radius r, it can be assumed that all lightning strikes with peak values higher than the corresponding current will be intercepted. As the imaginary sphere is rolled about the surfaces of the 3D digital model of the wind turbine, it is determined if the sphere is able to come in contact with the wind turbine prior to contacting an air termination system. There is risk of direct lightning attachment to the turbine where the sphere is able to come in contact with the wind turbine prior to contacting an air termination system.
[0040] Figures 1 through 9 depict example embodiments of a shrouded fluid turbine having two shrouds. Figure 1 is a perspective view of an exemplary embodiment of a shrouded fluid turbine of the present disclosure. Figure 2 is a front view of the fluid turbine of Figure 1. Figure 3 is a side view of the fluid turbine of Figure 1. Referring to Figure 1 through Figure 3, the shrouded fluid turbine 100 comprises a turbine shroud 110, an ejector shroud 120, a rotor 140, and a nacelle body 150. The turbine shroud 110 includes a front end 112, also known as an inlet end or a leading edge, and a rear end or trailing edge 116, also known as an exhaust end. The trailing edge 116 includes high energy lobes 117 and low energy lobes 115. The depiction of the recited high energy lobes 117 and low energy lobes 115 is solely for illustrative purposes. One of ordinary skill in the art will readily recognize that the shape and orientation of the lobes may take numerous forms and the illustrated embodiment is not intended to be limiting in scope. The ejector shroud 120 includes a front end 122, also known as an inlet end or leading edge, and a rear end or trailing edge 124, also known as an exhaust end. Support members 106 connect the turbine shroud 110 to the ejector shroud 120.
[0041] The rotor 140 surrounds the nacelle body 150 and comprises a central hub 141 at the proximal end of the rotor blades. The central hub 141 is rotationally engaged with the nacelle body 150. The rotor 140, turbine shroud 110, and ejector shroud 120 are coaxial with each other, i.e., they share a common central axis 105.
[0042] At least one air termination device 161, between 1/80 to 1/20 the diameter of the ejector in length, is engaged with the turbine shroud 110. Additionally, at least one air termination device 164 between lm and 2m in length is also engaged with the ejector shroud 120.
[0043] A Primary Lightning Protection system (LPS) is illustrated in Figures 1 through Figure 5. Figure 4 is a front view of an example embodiment, and Figure 5 is a side view of the example embodiment of Figure 4.
[0044] Figure 2 and Figure 3 depict a rolling sphere radius in relation to the outer surface of the fluid turbine 100. The rolling sphere circumference is illustrated by arc 170 and the radius is illustrated by arrow 172. The rolling sphere arcs 170 have an approximate diameter of 313 meters, which corresponds to a lightning current of up to 200 kA. It can be seen in Figures 2 and 3 that the arcs 170 do not come in contact with the body of the turbine shroud 110 or the ejector shroud 120 before coming in contact with at least one of the air termination devices 161/164. It can be further seen in Figures 2 and 3 that the arcs 170 do not come in contact with the rotor 140, the hub 141, or the nacelle 150 before coming in contact with at least one of the air termination devices 161/164. The air termination devices 161/164 are in electrical communication with a down conduction system 176 by way of electrically coupled first and second conductors 174/175. The down conduction system 176 transfers electricity to an earth- termination system 178 for dispersion of the electricity.
[0045] Figure 4 and Figure 5 depict a rolling sphere radius of approximately 80 meters, which corresponds to a lightning current in the range of approximately >25kA to <50 kA. The rolling sphere circumference is depicted by arcs 270 and the radius is depicted by arrow 272. It can be seen in Figure 4 and Figure 5 that the rolling sphere has minimal contact with the turbine shroud 210 and the ejector shroud 220. Simultaneous contact of the rolling sphere with either of the turbine shroud 210 or the ejector shroud 220 and at least one of the air termination devices 261/264 is possible. In such a situation, e.g., in the even of simultaneous contact, current is safely conducted to an earth-termination 278 system through the air termination devices 261/264 that are coupled with a down conduction system 276 by way of electrically coupled first and second conductors 274/275. This provides for the conduction of the current without significant damage to the turbine shroud 210 or the ejector shroud 220, due to the current range. It can be further seen in Figure 4 and Figure 5 that the arcs 270 do not come in contact with the rotor 240, the hub 241, or the nacelle 250 before coming in contact with at least one of the air termination devices 161/164.
[0046] A secondary lightning protection system (LPS2) is illustrated in Figure 6 and Figure 7. The LPS2 comprises electrically conductive materials integrated with the surfaces of a turbine shroud 310 and an ejector shroud 320. The electrically conductive materials are connected with a down conduction system 376 by way of electrically coupled first and second conductors 374/375, the down conduction system 376 is connected to an earth-termination system 378. Figure 6 and Figure 7 depict a rolling sphere radius of approximately 20 meters, which corresponds to a lightning current in the range of approximately >3kA to <10 kA. The rolling sphere circumference is depicted by arcs 370 and the radius is depicted by arrow 372. The LPS2 is intended to intercept and conduct lightning strikes of a range from approximately >3kA to <10 kA usually in the form of static electricity. Exposed hardware, for example, various metal fasteners (not shown) on the surface of the turbine shroud 310 and the ejector shroud 320 provide a sufficient means of dissipating a static charge prior to contact with the rotor 340, the hub 341, or the nacelle 350.
[0047] In addition to the protection provided by the air termination devices, shroud surfaces with embedded or integrated materials provide additional lightning protection to rotating and electrical generation components.
[0048] Figure 8 and Figure 9 illustrate an air-termination system integrated into the shroud surfaces. Referring to Figure 8, a mixer ejector turbine 400 comprises a turbine shroud 410 surrounding a rotor 440, engaged with a hub 441 that is further engaged with a nacelle 450. An ejector shroud 420 has an inner diameter greater that the outer diameter of the trailing edge of the turbine shroud 410 and the injector shroud 420 and the turbine shroud 410 are concentric to one another. In some embodiments the ejector shroud 420 surrounds the trailing edge of the turbine shroud 410. In some embodiments the ejector shroud 420 is located downstream from the trailing edge of the turbine shroud 410. A first electrically conductive material 470 is comprised of metalized polymers, fiber reinforced composites with electrically conductive fibers woven into the reinforcement, or composites with metallic characteristics such as those provided by nanoparticles made from graphite. The first electrically conductive material 470 is engaged with the leading edge of the turbine shroud 410 and further conductively engaged with an internal structure 472 of the turbine shroud 410 that is both electrically conductive and insulated. The internal structure 472 is further conductively engaged, through an electrical wiper system, as described below, with a down-conductive system 476 that is conductively engaged with an earth-termination system 478. A second electrically conductive material 475 is engaged with the trailing edge of the ejector shroud 420 and is further conductively engaged with an internal structure 474 of the ejector shroud 420 that is further conductively engaged with the down-conductive system 476 that is conductively engaged with the earth-termination system 478.
[0049] Electrical wiper systems, also known as slip rings, are commonly used to transfer electricity between stationary and rotating components and include conductive arms engaged with rotating disks. The conductive arms are often formed of metal such as brass or copper with a combination carbon and metallic substance at the distal ends. The distal ends engage with the rotating disks and provide rotational electrical connectivity.
[0050] Referring to Figure 9, a mixer ejector turbine 500 comprises a turbine shroud 510 that surrounds a rotor 540, engaged with a hub 541 that is further engaged with a nacelle 550. An ejector shroud 520 has an inner diameter greater than the outer diameter of the trailing edge of the turbine shroud 510, and the ejector shroud 520 and the turbine shroud 510 are concentric with one another. In some embodiments the ejector shroud 520 surrounds the trailing edge of the turbine shroud 510. In some embodiments the ejector shroud 520 is located downstream from the trailing edge of the turbine shroud 510. A first electrically conductive material 580 is integrated into the surface of the turbine shroud 510 and further conductively engaged with an internal structure 572 of the turbine shroud that is conductively engaged 510 that is electrically conductive and insulated. The internal structure 527 is further conductively engaged with a down- conductive system 576 that is conductively engaged to an earth-termination system 578. A second electrically conductive material 586 is integrated into the surface of the ejector shroud 520 and is further conductively engaged with an internal structure 574 of the ejector shroud 520 that is electrically conductive and insulated. The internal structure 574 is further conductively engaged with the down-conductive system 576 that is conductively engaged to the earth-termination system 578.
[0051 ] Figures 10 through 12 depict example embodiments of a single shroud fluid turbine. Figure 10 is a perspective view of an exemplary embodiment of a single shroud fluid turbine of the present disclosure. Figure 11 is a front view of the single shroud fluid turbine of Figure 10. Figure 12 is a side view of the single shroud fluid turbine of Figure 10. Referring to Figure 10 through Figure 12, the single shrouded fluid turbine 600 comprises a turbine shroud 610, a rotor 640, and a nacelle body 650. The turbine shroud 610 includes a front end 612, also known as an inlet end or a leading edge, and a rear end or trailing edge 616, also known as an exhaust end. The trailing edge 616 includes high energy lobes 617 and low energy lobes 615.
[0052] The rotor 640 surrounds the nacelle body 650 and includes a central hub 641 at the proximal end of the rotor blades. The central hub 641 is rotationally engaged with the nacelle body 650. The rotor 640 and turbine shroud 610 are coaxial with each other, i.e., they share a common central axis 605. [0053] At least one air termination device 661, between 1/80 to 1/20 the diameter of the turbine shroud 610 in length, is engaged with the leading edge 612 of the turbine shroud 610. Additionally, at least one air termination device 664 between lm and 2m in length is also engaged with the trailing edge 616 of the turbine shroud 610.
[0054] A Primary Lightning Protection system (LPS) is illustrated in Figures 10 through Figure 12. Figure 11 is a front view of an example embodiment, and Figure 12 is a side view of the example embodiment of Figure 11.
[0055] Figure 11 and Figure 12 depict a rolling sphere radius in relation to the outer surface of the fluid turbine 600. The rolling sphere circumference is illustrated by arc 670 and the radius is illustrated by arrow 672. The rolling sphere arcs 670 have an approximate diameter of 313 meters, which corresponds to a lightning current of up to 200 kA. It can be seen in Figures 11 and 12 that the arcs 670 do not come in contact with the body of the turbine shroud 610 before coming in contact with at least one of the air termination devices 661/664. It can be further seen in Figures 11 and 12 that the arcs 670 do not come in contact with the rotor 640, the hub 641, or the nacelle 650 before coming in contact with at least one of the air termination devices 661/664. The air termination devices 661/664 are in electrical communication with a down conduction system 676 by way of an electrically coupled conductor 675. The down conduction system 676 transfers electricity to an earth-termination system 678 for dispersion of the electricity.
[0056] Although a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

Claims

CLAIMS:
1. A fluid turbine lightning protection system, comprising:
at least one air termination device positionable on a shroud of a fluid turbine, the air termination device formed at least in part of an electrically conductive material; a down conduction system in electrical communication with the at least one air termination device; and
an earth-termination system in electrical communication with the down conduction system, the earth-termination system configured to dissipate electricity to the ground,
wherein the at least one air termination device is configured to intercept a lightning strike.
2. The fluid turbine lightning protection system of Claim 1, wherein the at least one air termination device comprises a plurality of air termination devices positioned on the shroud of the fluid turbine and configured to intercept a lightning strike based on a "Rolling Sphere" derivation.
3. The fluid turbine lightning protection system of Claim 2, wherein the "Rolling Sphere" derivation is derived from the equation r = 10 · I0'65, where I is defined as the peak current in kiloamperes and r is defined as the rolling sphere radius in meters.
4. The fluid turbine lightning protection system of Claim 1 , wherein the fluid turbine includes an ejector shroud and at least one air termination device is positionable on the ejector shroud.
5. The fluid turbine lightning protection system of Claim 1, wherein the shroud of the fluid turbine further includes:
an external electrically conductive material; and
an internal electrically conductive material,
wherein the external electrically conductive material is conductively engaged with the internal electrically conductive material, and the internal electrically conductive material is electrically engaged with the down conduction system.
6. The fluid turbine lightning protection system of Claim 5, wherein the internal electrically conductive material is in electrical communication with the down conductive system through a electrical wiper system.
7. The fluid turbine lightning protection system of Claim 5, wherein the external electrically conductive material is positioned at a leading edge of the turbine shroud.
8. The fluid turbine lightning protection system of Claim 5, wherein the internal electrically conductive material is integrated with the surface of the turbine shroud.
9. The fluid turbine lightning protection system of Claim 4, wherein the ejector shroud further comprises:
an external electrically conductive material; and
an internal electrically conductive material,
wherein the external electrically conductive material is conductively engaged with the internal electrically conductive material, and the internal electrically conductive material is electrically engaged with the down conduction system.
10. The fluid turbine lightning protection system of Claim 9, wherein the internal electrically conductive material is in electrical communication with the down conductive system through an electrical wiper system.
11. The fluid turbine lightning protection system of Claim 9, wherein the external electrically conductive material is positioned at a trailing edge of the ejector shroud.
12. The fluid turbine lightning protection system of Claim 9, wherein the internal electrically conductive material is integrated with the surface of the ejector shroud.
13. A lightning protected fluid turbine, comprising:
a fluid turbine including a shroud;
at least one air termination device positioned on the shroud of the fluid turbine, the air termination system formed at least in part of an electrically conductive material; a down conduction system in electrical communication with the at least one air termination device; and
an earth-termination system in electrical communication with the down conduction system, the earth-termination system configured to dissipate electricity to the ground,
wherein the at least one air termination device is configured to intercept a lightning strike so as to prevent the lightning from striking the fluid turbine.
14. The lightning protected fluid turbine of Claim 13, wherein the at least one air termination device comprises a plurality of air termination devices positioned on the shroud of the fluid turbine and configured to intercept a lightning strike based on a "Rolling Sphere" derivation.
15. The lightning protected fluid turbine of Claim 14, wherein the "Rolling Sphere" derivation is derived from the equation r = 10 · I0'65, where I is defined as the peak current in kiloamperes and r is defined as the rolling sphere radius in meters.
16. The lightning protected fluid turbine of Claim 13, wherein the fluid turbine includes an ejector shroud and at least one air termination device is positionable on the ejector shroud.
17. The lightning protected fluid turbine of Claim 13, wherein the shroud of the fluid turbine further includes:
an external electrically conductive material; and
an internal electrically conductive material,
wherein the electrically conductive material is conductively engaged with the internal electrically conductive material, and the internal electrically conductive material is electrically engaged with the down conduction system.
18. The lightning protected fluid turbine of Claim 17, wherein the internal electrically conductive material is in electrical communication with the down conductive system through an electrical wiper system.
19. The lightning protected fluid turbine of Claim 17, wherein the external electrically conductive material is positioned at a leading edge of the shroud of the fluid turbine.
20. The lightning protected fluid turbine of Claim 17, wherein the internal electrically conductive material is integrated with the surface of the shroud of the fluid turbine.
21. The lightning protected fluid turbine of Claim 16, wherein the ejector shroud further includes:
an external electrically conductive material; and
an internal electrically conductive material,
wherein the electrically conductive material is conductively engaged with the internal electrically conductive material, and the internal electrically conductive material is electrically engaged with the down conduction system.
22. The lightning protected fluid turbine of Claim 21, wherein the internal electrically conductive material is in electrical communication with the down conductive system through an electrical wiper system.
23. The lightning protected fluid turbine of Claim 21, wherein the external electrically conductive material is positioned at a trailing edge of the ejector shroud.
24. The lightning protected fluid turbine of Claim 21, wherein the internal electrically conductive material is integrated with the surface of the ejector shroud.
25. A method of protecting a fluid turbine from a lightning strike, comprising:
providing a fluid turbine including a shroud;
determining a peak lightning strike current;
calculating a "Rolling Sphere" circumference or radius based on the equation: r = 10 · I0'65, where I is defined as the peak lightning strike current in kiloamperes and r is defined as the rolling sphere radius in meters; and positioning one or more air termination devices on the shroud that are in electrical communication with a down conduction system that is in electrical communication with a earth-termination system,
wherein the one or more air termination devices are positioned on the shroud such that the calculated "Rolling Sphere" contacts the one or more air termination devices before contacting the shroud when the "Rolling Sphere" is rolled along an exterior of the shroud.
26. The method of protecting a fluid turbine from a lightning strike of Claim 25, wherein the fluid turbine is provided with an ejector shroud and one or more air termination devices are positioned on the ejector shroud.
27. The method of protecting a fluid turbine from a lightning strike of Claim 25, wherein the shroud includes an electrically conductive material integrated therein and in electrical communication with the down conduction system.
28. The method of protecting a fluid turbine from a lightning strike of Claim 27, wherein the electrically conductive material is positioned at a leading edge of the shroud.
29. The method of protecting a fluid turbine from a lightning strike of Claim 27, wherein the electrically conductive material is integrated with a surface of the shroud.
EP12806193.4A 2011-09-14 2012-09-14 Fluid turbine lightning protection system Active EP2756187B1 (en)

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PL229386B1 (en) * 2015-08-25 2018-07-31 Staszor Roman Jan Tunnel wind turbine with horizontal axis of rotor rotation
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US20080095624A1 (en) * 2006-10-19 2008-04-24 Bastian Lewke Lightning protection of wind turbines
US9450392B2 (en) * 2007-12-28 2016-09-20 Vestas Wind Systems A/S Method for detection of charge originating from lightning
WO2010005289A2 (en) * 2008-07-11 2010-01-14 Donqi Quandary Innovations Bv Wind turbine with di ffuser
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WO2013040361A3 (en) 2013-05-10
EP2756187B1 (en) 2016-06-08

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